PROJECT SUMMARY Head and neck cancer survivors face demanding and distressing nutritional challenges and their caregivers often feel unprepared to carry out nutritional support efforts at home after treatment. This study builds on our team's previous research in which we developed a survivorship needs assessment planning tool to assess the specialized needs of head and neck cancer survivors and caregivers and generate personalized care plans. The system has demonstrated high acceptability and feasibility and has promising potential for expansion to support caregivers' nutritional support efforts beyond the clinic by capitalizing on mobile technology to follow caregivers as they transition home in the high-need recovery period. In the current mixed methods research, working with survivors, caregivers and health care providers, we will develop and pilot-test a nutrition-focused mobile support system (mSupport) for head and neck cancer dyads as they manage nutritional needs and concerns during the initial recovery period. The specific aims of this R21 are to 1) develop and pretest a mobile nutritional support system (needs assessment tool, tailored care plan and mobile messaging program) for head and neck cancer caregivers at the end of treatment and 2) pilot-test the mobile support system in head and neck cancer dyads. We will use dyadic interviews with head and neck cancer survivors and their caregivers (N=15 dyads) and surveys with a national panel of oncology dieticians (N=35) to characterize nutritional support needs and develop the mSupport system. After finalizing the system with our Clinical Advisory Board, we will pilot the finalized system in the clinic with 30 survivor-caregiver dyads (N=60 participants) and provide bi-weekly caregiver mobile monitoring and support (encouragement, reminders and tips delivered through messaging and peer videos) for 4 weeks, tracking feasibility, acceptability and short-term outcomes for a future randomized controlled trial. This research is novel in its dyadic approach to survivorship care planning, its focus on nutritional wellness to accelerate dyads' readiness to transition from treatment to the post-treatment period and its extension of a scalable mobile health support system to reach caregivers. Results will lead to a large-scale multi-site trial to improve head and neck cancer survivorship care.